Patterson and Paetro gave it away on the dust jacket blurb, "The Women's Murder Club faces an unspeakable horror in an irresistible hospital and courtroom thriller ...". The problem is, they weren't talking about one novel being two things at once. They were talking about two separate novellas that had nothing to do with one another being tossed into a blender and combined into a single novel.
The bad news first! The first story is a typical and seriously overused hospital plot - a series of inexplicable hospital deaths that ultimately and not particularly surprisingly come down to the runaway serial murderer roaming the halls of a creepy hospital. The other is an uninspired police procedural about the apprehension of a kinky serial killer who liked to kill young girls and dress them up a little after they were already dead.
The good news is that, unlike "You've Been Warned" which was a complete waste of even the energy needed to turn the pages, the writing in "The 5th Horseman" manages to be snappy, entertaining and actually quite compelling. The novel is diverting and enjoyable despite its obvious shortcomings. At the same time as I was aware of the weaknesses in the plot's originality, I was definitely hooked and unwilling to put the book down and let it go. I can't help but admit that's a good thing!
Despite the fact that Patterson's reputation as a novelist is hanging by the thinnest of threads, I recommend "The 5th Horseman" as a thoroughly enjoyable, if entirely forgettable piece of literary brain candy. Take it on the plane or to the beach by all means.